Author Correction: Strain rate dependency of dislocation plasticity (original) (raw)
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Averaging in dislocation mediated plasticity
International Journal of Engineering Science, 2020
Starting from the assumption that all possible orientations of grains are equally probable, we evaluate the mean resolved shear stress and strains in polycrystalline bars subjected to axially symmetric tension or compression. The evaluated quantities, in combination with the kinetics of thermally activated dislocation depinning, are used to establish the equation for the stress rate. We then perform a large-scale least-square analysis to identify the physics based parameters of this theory and show that the simulated stress-strain curves for copper, iron and steel agree well with the experiments of Johnson and Cook.
Strain rate dependency of dislocation plasticity
Nature Communications, 2021
Dislocation glide is a general deformation mode, governing the strength of metals. Via discrete dislocation dynamics and molecular dynamics simulations, we investigate the strain rate and dislocation density dependence of the strength of bulk copper and aluminum single crystals. An analytical relationship between material strength, dislocation density, strain rate and dislocation mobility is proposed, which agrees well with current simulations and published experiments. Results show that material strength displays a decreasing regime (strain rate hardening) and then increasing regime (classical forest hardening) as the dislocation density increases. Accordingly, the strength displays universally, as the strain rate increases, a strain rate-independent regime followed by a strain rate hardening regime. All results are captured by a single scaling function, which relates the scaled strength to a coupling parameter between dislocation density and strain rate. Such coupling parameter al...
Scripta Materialia, 2003
The relations between mesoscopic plastic strain gradients, Ôgeometrically necessaryÕ dislocations (GND), and dislocation dynamics are discussed. It is argued that the connection between GND and size effects in crystal plasticity should be established on the basis of dislocation dynamics, taking into account the specific deformation conditions. It is demonstrated that dislocation dynamics based models for size effects lead to different phenomenological forms of gradient plasticity ÔlawsÕ proposed in the literature.
The crucial role of chemistry on mobile properties of dislocation
Philosophical Magazine, 2010
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Computational Methods for Microstructure-Property Relationships, 2010
Plasticity of crystalline solids is a dynamic phenomenon resulting from the motion under stress of linear crystal defects known as dislocations. Such a statement is grounded on numerous convincing observations, and it is widely accepted by the scientific community. Nevertheless, the conventional plasticity theories use macroscopic variables whose definition does not involve the notion of dislocation. This paradoxical situation arises from the enormous range covered by the length scales involved in the description of plasticity, from materials science to engineering. It may have seemed impossible to account for the astounding complexity of the (microscopic) dynamics of dislocation ensembles at the (macroscopic) scale of the mechanical properties of materials. Justifications offered for such a simplification usually reside in perfect disorder assumptions. Namely, plastic strain is regarded as resulting from a large number of randomly distributed elementary dislocation glide events, showing no order whatsoever at any intermediate length scale. Hence, deriving the mechanical properties from the interactions of dislocations with defects simply requires averaging on any space and time domain. The existence of grain boundaries in polycrystals is of course affecting this averaging
Finite strain discrete dislocation plasticity
Journal of the Mechanics and Physics of Solids, 2003
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Recent Progress in Dislocation Studies Using Bias Stress Experiments
Le Journal de Physique Colloques, 1985
Resume-De recents progres ont @t@ r@alis@s dans l ' u t i l i s a t i o n de l a technique de mesure par couplage d'une contrainte quasi-statique a avec une mesure de llatt@nuation a e t de la vitesse v d'ultrasons. Ces progres sont l i e s ti l ' u t i l i s a t i o n d'une contrainte cyclique basse frequence qui permet de tracer des courbes fermees Aa(a) e t Av/v(a) dont l a forme e t l'@volution sont caracteristiques pour chaque m6canisme pouvant contrdler l e mouvement des dislocations.
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